A three-step development strategy for 3D printable concrete containing coarse aggregates

Abstract

The use of coarse aggregates in 3D printable concrete (3DPC) reduces the amount of cement. However, it presents challenges for 3D printing process. In this study, a three-step strategy is proposed for the development of 3DPC, containing coarse aggregates with a maximum particle size of 20 mm. This strategy integrates all stages of the 3D printing process, categorizing the stages of the concrete into the flow-state stage, the structural build-up stage, and the hardened-state stage. The 3DPC mix ratio is determined on the basis of experimental testing and predictive modeling. Experimental studies are conducted, using the mix ratios obtained from this strategy, followed by trial printing tests. The results indicate the usefulness of the three-step strategy. It is efficient to control the flowability in the flow-state stage and the mechanical properties in the structural build-up stage of 3DPC by adjusting the dosage of polycarboxylate ether superplasticizer and aluminum sulfate-based accelerator.